The push towards Internet Protocol version six (IPv6) is largely due to IP address space exhaustion associated with legacy Internet Protocol version 4 (IPv4) networks. In an ideal world, a transition from IPv4 to IPv6 would take place overnight, thereby resolving any IP address space issues. However, the present reality is that for a considerable period of time there will be devices and networks that will have to support both IPv4 and IPv6. During this transition period, dual stack devices that support both IPv4 and IPv6 must utilize a scarce resource—an IPv4 address. Therefore efficient utilization of IP address space in network devices supporting multiple IP stacks, including the IPv4 stack, is paramount for preventing exhaustion of limited IPv4 address space and corresponding network resources.
While attempts have been made to address IPv4 address space exhaustion, existing solutions fail to provide independent control of multi-stack IP network layer sessions. For instance, U.S. Publication No. 2006/0165093 employs a “hang time” parameter for establishing and terminating IPv4 and IPv6 network layer sessions in dual-stack devices for purposes of sharing the link layer resources between the two sessions and to provide detailed accounting functionality. However, the “hang time” parameter does not allow independent control of each network layer session because it is not dedicated to a particular version of the IP stack. Furthermore, activation of the “hang time” parameter happens upon termination of one of the network layer sessions.
U.S. Publication No. 2007/0136601 deals with the problem of IPv4 address space exhaustion using an entirely different approach, which entails requiring user input to authenticate a request to assign an IPv4 address to an IPv6 node, rather than providing independent control of each network layer session.